<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      button.active{
        color: red;
      }
      .content{
        width: 200px;
        height: 200px;
        text-align: center;
        line-height: 200px;
        border: 1px solid #333;
      }
    </style>
  </head>
  <body>
    <div id="app">
       <button @click="switchTab(0)" :class="{active: activeIndex===0}">标题1</button>
       <button @click="switchTab(1)" :class="{active: activeIndex===1}">标题2</button>
       <button @click="switchTab(2)" :class="{active: activeIndex===2}">标题3</button>
       <div class="content" v-show="activeIndex===0">内容1</div>
       <div class="content" v-show="activeIndex===1">内容2</div>
       <div class="content" v-show="activeIndex===2">内容3</div>
    </div>

    <script src="./vue.global.js"></script>
    <script>
      const { createApp } = Vue;
      const app = createApp({
        data() {
          return {
            activeIndex: 0
          };
        },
        methods: {
          switchTab(index) {
            this.activeIndex = index;
          }
        },
      });
      app.mount("#app");
    </script>
  </body>
</html>
